A Study of ARGX-110 in Combination With Azacytidine in Participants With Newly Diagnosed Acute Myeloid Leukemia (AML) or High Risk Myelodysplatic Syndrome (MDS)

A Phase I/II, Open-label, Dose-Escalating Study With a Proof of Concept Cohort to Evaluate the Safety, Tolerability and Efficacy of ARGX-110 in Combination With Azacytidine in Subjects With Newly Diagnosed Acute Myeloid Leukemia (AML) or High Risk Myelodysplatic Syndrome (MDS)

The purpose of this study is to determine the maximum tolerated dose (MTD) of ARGX-110 and/or the recommended Phase II dose (RP2D) in combination with a standard dose of azacytidine (AZA) in Phase 1; and to evaluate efficacy of ARGX-110 when administered at a RP2D level established in Phase I in combination with a standard dose of AZA (proof-of concept) by evaluating overall response rate (ORR) in Phase 2.

Inclusion Criteria:

• Signed informed consent form (ICF) indicating an understanding of the purposes, risks, and procedures required for the study and willingness and ability to participate in the study
• Acute myeloid leukemia (AML) or high risk myelodysplastic syndrome (MDS) (according to 2016 World Health Organization [WHO] classification definition of greater than or equal to [>=] 20 percent [%] blasts) (bone marrow) unsuitable for intensive treatment (including stem cell transplantation) with a curative intent, but eligible to receive azacytidine (AZA) treatment
• Expected life expectancy >= 3 months, at the discretion of the investigator
• Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2
• Women of childbearing potential having a negative serum pregnancy test at screening and within 48 hours before infusion of ARGX-110 on Day -14, and willing to use an effective contraceptive method (intrauterine devices, hormonal contraceptives, contraceptive pill, implants, transdermal patches, hormonal vaginal devices, infusions with prolonged release) during the study and for at least 3 months after the last study drug administration

Exclusion Criteria:

• Prior or concurrent malignancy, except for the following: (1) adequately treated basal cell or squamous cell skin cancer; (2) carcinoma in situ of the cervix; (3) carcinoma in situ of the breast; (4) incidental histological finding of Prostate cancer (Tumour, Node, Metastasis [TNM] stage T1a or T1b), or; (5) Any other cancer from which the subject has been disease-free for more than 2 years
• Any previous AML or MDS chemo- or radiotherapy (with the exception of hydroxyurea/Litalir for leukocyte control which should be discontinued by the first day of AZA, local radiation therapy, therapy for basal or squamous cell carcinoma of the skin)
• Treatment with any investigational product within 4 weeks before the first administration of ARGX-110
• Any known active or chronic infection, including human immunodeficiency virus (HIV) and hepatitis B or C virus infection
• Any other concurrent disease or medical condition that is likely to interfere with study procedures or results, or that in the opinion of the investigator would constitute a hazard for participating in this study